fix flake8 repo

Author: sdebruyn

.pre-commit-config.yaml

@@ -65,7 +65,7 @@ repos:
           - '--target-version=py39'
           - '--check'
           - '--diff'
-  - repo: 'https://gitlab.com/pycqa/flake8'
+  - repo: 'https://github.com/pycqa/flake8'
     rev: 3.9.2
     hooks:
       - id: flake8